1.Field of the Invention
The present invention relates to optical fiber cables and, more particularly, to optical fiber cables having fibers contained therein having various lengths.
2.Description of the Prior Art
Traditional copper wire communication cable carries a plurality of copper conductors which extend over the entire length of the cable. When such communication cables are used for outside plant systems and subscriber loops, a particular size cable having a predetermined number of conductors is used between termination points. At a point where lines are dropped to local homes or buildings, or to terminals in a subscriber loop, a splice is made to a separate smaller sized cable to facilitate the continuation of the fewer number of copper conductors to the next termination point. Thus, as one proceeds along the transmission line, the number of conductors is reduced at each termination point. This procedure of using progressively smaller-sized cables does not create any significant problem, since copper conductors can be easily spliced without significant signal loss or expense.
With optical fibers, the above method of providing outside plant systems and subscriber loops is not practical or cost effective. The continuing fibers of one cable cannot be easily spliced to the fibers of a smaller cable without realizing undesirable signal attenuation at the splice points and considerable costs.
In an effort to reduce splice cost and signal loss, an alternative was used in some cases. A single large-sized optical fiber cable was used throughout a distribution system. The cable contained the maximum number of optical fibers required, so that the need for splicing would be eliminated. At a termination point, a particular fiber or fibers would be accessed from the cable. The fiber or fibers would be cut and connected to a local terminal or cable. The remaining fibers would be undisturbed and would continue along the remaining length of the cable. However, the remaining length of the accessed fibers would be unused and wasted.
A significant cost of an optical fiber cable resides in the cost of the optical fibers contained therein. In the above-mentioned arrangement, a large portion of the fiber remained unused downstream from the termination points and represented a waste of expensive fiber, the cost of which was included in the overall cable cost.
Assuming an even distribution of termination points along the length of a fiber optic cable, fifty percent of the fiber contained within the cable would be unused and wasted. This unused fiber would represent a high percentage of the overall cost of the cable. Thus, while this alternative reduced splice cost and signal loss, a significant cost in unused fibers was realized.